The present invention generally relates to disc-shaped recording medium reproducing apparatuses, and more particularly to a disc-shaped recording medium reproducing apparatus capable of placing and leaving a disc-shaped information recording medium in a state possible for reproduction within the reproducing apparatus when a case having a lid for accommodating the recording medium therein is inserted into and then pulled out from within the reproducing apparatus, and also capable of incasing the recording medium within the case so that the recording medium can be obtained outside the reproducing apparatus together with the case, when the empty case is inserted into and then pulled out from within the reproducing apparatus. The present invention further and especially relates to an improvement of a disc-shaped recording medium reproducing apparatus having guide rails for guiding sliders which support the case at the left and right ends thereof, to move therealong when the case for recording medium is inserted into and then pulled out from within the reproducing apparatus.
Conventionally, in an apparatus for reproducing a disc-shaped recording medium (referring to video disc, PCM audio disc, and the like, and hereinafter simply referred to as a disc), there are types of apparatuses in which a disc is reproduced when the disc is loaded upon holding and placing of the disc within the reproducing apparatus, by inserting into and then pulling out a disc case which has a lid and accommodates a disc therein, from within the reproducing apparatus. As a conventional apparatus of this type, there is an apparatus which cooperates with a disc case comprising a rigid jacket for accommodating a disc, and a tray having a front part which is engaged by engaging means upon complete insertion of the disc case within the reproducing apparatus and an annular or ring portion fixed to the front part for encircling the outer periphery of the disc. This conventional reproducing apparatus is constructed so that when this disc case is inserted within the reproducing apparatus to a predetermined position, the engaging means of the reproducing apparatus engages to and holds onto the front part of the tray. Hence, when the jacket is pulled out from within the reproducing apparatus, the disc is held by the annular portion of the tray and relatively slipped out from the jacket at the above predetermined position, and the outer peripheral edge part of the disc rests on and is supported by a supporting mechanism within the reproducing apparatus. Then, a turntable relatively rises within the inner side of the supporting mechanism, and the disc is placed onto and is unitarily rotated with the turntable, to perform the reproduction. After completion of the reproduction, when the empty jacket is inserted into the reproducing apparatus, the disc is relatively inserted into the jacket together with the annular portion of the tray, and the engagement of the engaging means is released. Accordingly, when the jacket is pulled out from the reproducing apparatus, the disc and the tray is obtained outside the reproducing apparatus together with the jacket in a state in which the disc and the tray is incased inside the jacket.
Thus, in the above disc case, for use with the conventional reproducing apparatus, the peripheral side surface of the disc is held by the engaged annular portion of the tray and the disc remains within the reproducing apparatus upon pulling of the jacket outside the reproducing apparatus. Accordingly, a supporting mechanism which is placed with the remaining disc thereon and supports the outer peripheral edge part of the disc, is provided in the reproducing apparatus. Hence, the turntable must be constructed so as to relatively move up-and-down within the inner side of the supporting mechanism. This means that the diameter of the turntable must be smaller than the diameter of the disc, and the outer peripheral edge part of the turntable thus makes contact with and supports the disc at the signal recording surface which is to the inner side of the outer peripheral edge part of the lower disc surface. Therefore, scratches are easily made on the signal recording surface part of the disc which is supported by the turntable, and especially when starting the rotation of the turntable, suffers a disadvantage in that scratches are more easily made in this case due to a force acting in a direction so as to rub the disc. Accordingly, when the disc is used many times, fine reproduction cannot be obtained due to the above scratches formed on the signal recording surface of the disc.
Moreover, upon reproduction, when a reproducing transducer of the reproducing apparatus moves to the position of the signal recording surface on the disc surface, the reproducing transducer must traverse over the annular portion of the tray. This traversing movement accordingly leads to a disadvantage in that the reproducing transducer moving mechanism must be designed so that the reproducing transducer does not collide with the annular portion, and the construction of the mechanism thus becomes complex.
Accordingly, in United States patent application Ser. No. 231,868, filed on Feb. 5, 1981 and entitled "DISC-SHAPED RECORDING MEDIUM REPRODUCING APPARATUS" in which the assignee is the same as that of the present application, a reproducing apparatus was proposed which cooperates with a disc case having a jacket which has a space for accommodating a disc and an opening for allowing the disc to go in and out of the jacket, and a lid member inserted through the opening of the jacket for closing the opening of the jacket, where the reproducing apparatus comprises an inserting opening through which the case is inserted, a turntable for rotating the disc, holding means for holding at least one of the disc and the lid member provided at an inner-most part on the opposite side from the inserting opening with respect to the turntable, lowering and raising means for lowering the disc to a position where the disc is placed on the turntable from a holding position where the disc is held by the holding means upon starting of the reproduction and raising the disc to the holding position from the turntable upon finishing or discontinuing of the reproduction, a reproducing transducer for reproducing the disc placed on the turntable, and moving means for moving the reproducing transducer from a waiting position to a reproducing position with respect to the disc.
On the other hand, upon loading and unloading of the disc, the disc case is supported at the left and right ends on a front side with respect to inserting direction by corresponding sliders movable along their guide rails and is inserted into and pulled out from the apparatus. The guide rails are disposed at either sides of a disc case moving passage, and must be at a height position where the guide rails are not in a way of a pickup frame. In this connection, the guide rails were disposed at a position higher than the pickup frame, which results in large height dimension of the reproducing apparatus by that much.
In the above stated application entitled "DISC-SHAPED RECORDING MEDIUM REPRODUCING APPARATUS", is disclosed a guide rail structure which enables the reproducing apparatus to be flat shape. This guide rail structure comprises a front end rail part, a center rail, and a rear end rail part which are separated with each other. The front end and rear end rail parts are fixed to the reproducing apparatus, while the center rail part is fixed to the side surface of a pickup frame and moves together with the pickup frame. When the pickup frame is returned to the waiting position, the center rail part is aligned with the other rail parts.
This guide rail structure, however, is not provided with means for aligning the moving center rail part with the front and rear fixed rail parts when the pickup frame is returned to the waiting position, which therefore involves any possibility of occurring of misalignment. When misalignment occurs, the disc case inserting operation is interfered in halfway, whereby the disc loading and unloading operation become impossible.